Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G65/00—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule
  • C08G65/02—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from cyclic ethers by opening of the heterocyclic ring
  • C08G65/26—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from cyclic ethers by opening of the heterocyclic ring from cyclic ethers and other compounds
  • C08G65/2642—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from cyclic ethers by opening of the heterocyclic ring from cyclic ethers and other compounds characterised by the catalyst used
  • C08G65/2645—Metals or compounds thereof, e.g. salts
  • C08G65/2663—Metal cyanide catalysts, i.e. DMC's
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G65/00—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule
  • C08G65/02—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from cyclic ethers by opening of the heterocyclic ring
  • C08G65/04—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from cyclic ethers by opening of the heterocyclic ring from cyclic ethers only
  • C08G65/22—Cyclic ethers having at least one atom other than carbon and hydrogen outside the ring
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G65/00—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule
  • C08G65/02—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from cyclic ethers by opening of the heterocyclic ring
  • C08G65/26—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from cyclic ethers by opening of the heterocyclic ring from cyclic ethers and other compounds
  • C08G65/2603—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from cyclic ethers by opening of the heterocyclic ring from cyclic ethers and other compounds the other compounds containing oxygen
  • C08G65/2606—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from cyclic ethers by opening of the heterocyclic ring from cyclic ethers and other compounds the other compounds containing oxygen containing hydroxyl groups
  • C08G65/2609—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from cyclic ethers by opening of the heterocyclic ring from cyclic ethers and other compounds the other compounds containing oxygen containing hydroxyl groups containing aliphatic hydroxyl groups
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G2650/00—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule
  • C08G2650/28—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule characterised by the polymer type
  • C08G2650/58—Ethylene oxide or propylene oxide copolymers, e.g. pluronics

Definitions

• the invention relates to a process for controlling the molar mass distribution in the alkoxylation of hydroxyl compounds with epoxide monomers by means of double metal cyanide catalysts using specific hydrosiloxanes and silanes as additives which have at least one hydridic hydrogen atom bonded directly to the silicon atom.
• Polyether alcohols often also known simply and used synonymously as polyethers or polyetherols for short, have been known for some time and are prepared industrially in large amounts and serve, among other uses, through reaction with polyisocyanates, as starting compounds for preparing polyurethanes or else for the preparation of surfactants.
• Most processes for preparing alkoxylation products (polyethers) make use of basic catalysts, for example of the alkali metal hydroxides and of the alkali metal methoxides. Particularly widespread and known for many years is the use of KOH.
• a usually low molecular weight hydroxy-functional starter such as butanol, allyl alcohol, propylene glycol or glycerol
• an alkylene oxide such as ethylene oxide, propylene oxide, butylene oxide or a mixture of different alkylene oxides
• the strongly alkaline reaction conditions in this so-called living polymerization promote various side reactions. Rearrangement of propylene oxide to allyl alcohol, which itself functions as a chain starter, and chain termination reactions, form polyethers with a relatively wide molar mass distribution and unsaturated by-products.
• the alkoxylation reaction performed under alkaline catalysis also affords propenyl polyethers.
• These propenyl polyethers are found to be unreactive by-products in the hydrosilylating further processing to give SiC-supported silicone polyether copolymers and are additionally—as a result of the hydrolytic liability of the vinyl ether bond present therein and release of propionaldehyde—the undesired source of olfactory product defects. This is described, for example, in EP-A-1431331 (U.S. 2004-132951).
• acid catalyzes are also known for alkoxylation.
• DE 10 2004 007561 U.S. 2007-185353 describes the use of HBF 4 and of Lewis acids, for example BF 3 , AlCl 3 and SnCl 4 , in alkoxylation technology.
• a disadvantage in the acid-catalyzed polyether synthesis is found to be the inadequate regioselectivity in the ring-opening of unsymmetrical oxiranes, for example propylene oxide, which leads to polyoxyalkylene chains with some secondary and primary OH termini being obtained in a manner without any obvious means of control.
• unsymmetrical oxiranes for example propylene oxide
• a workup sequence of neutralization, distillation and filtration is indispensable here too.
• ethylene oxide is introduced as a monomer into the acid-catalyzed polyether synthesis, the formation of dioxane as an undesired by-product is to be expected.
• the catalysts used to prepare polyether alcohols are, however, also frequently multimetal cyanide compounds or double metal cyanide catalysts, commonly also referred to as DMC catalysts.
• DMC catalysts minimizes the content of unsaturated by-products, and the reaction also proceeds with a significantly higher space-time yield compared to the customary basic catalysts.
• the preparation and use of double metal cyanide complexes as alkoxylation catalysts has been known since the 1960s and is detailed, for example, in U.S. Pat. No. 3,427,256, U.S. Pat. No. 3,427,334, U.S. Pat. No. 3,427,335, U.S. Pat. No. 3,278,457, U.S. Pat. No.
• the alkoxylation products prepared with DMC catalysts are notable for a much narrower molar mass distribution compared to alkali-catalyzed products.
• the high selectivity of the DMC-catalyzed alkoxylation is responsible for the fact that, for example, propylene oxide-based polyethers contain only very small proportions of unsaturated by-products.
• WO 98/03571 U.S. Pat. No. 5,689,012 describes a process for continuously preparing polyether alcohols by means of DMC catalysts, in which a mixture of a starter and a DMC catalyst is initially charged in a continuous stirred tank, the catalyst is activated, and further starter, alkylene oxides and DMC catalysts are added continuously to this activated mixture, and, on attainment of the target fill level of the reactor, polyether alcohol is drawn off continuously.
• JP 06-16806 refers to a process for continuously preparing polyether alcohols by means of DMC catalysts, likewise in a continuous stirred tank or in a tubular reactor, in which an activated starter substance mixture is initially charged at the inlet and alkylene oxide is metered in at various points in the tubular reactor.
• DD 203 725 also refers to a process for continuously preparing polyether alcohols by means of DMC catalysts, in which an activated starter substance mixture is initially charged at the inlet in a tubular reactor and alkylene oxide is metered in at various points in the tubular reactor.
• WO 01/62826 (U.S. Pat. No. 6,673,972), WO 01/62824 (U.S. Pat. No. 7,022,884) and WO 01/62825 (U.S. Pat. No. 6,664,428) refers to specific reactors for the continuous process for preparing polyether alcohols by means of DMC catalysts.
• polyetherols which have been obtained via DMC catalysis and have been characterized by their narrow molecular weight distribution are limited especially where the intention is to use them as copolymer components in silicone polyether copolymers which are involved in polyurethane foam systems, for example, as interface-active substances (PU foam stabilizers).
• This industrially significant substance class is notable in that, even in a small dosage in the PU system to be foamed, it controls to a considerable degree the morphological characteristics thereof and hence the later use property of the foam parts obtained.
• the high chemical purity and low polydispersity of the polyetherols prepared by means of DMC catalysts is desirable on the one hand, but, on the other hand, the DMC catalysis causes such a different kind of structure of the polyether chain compared to conventional, alkali-catalyzed polyethers that DMC-based polyetherols are suitable as precursors for interface-active polyether siloxanes only with high limitations.
• the usability of the usually allyl alcohol-started polyetherols described in the field of PU foam stabilizers is limited to a relatively small group of polyetherols which consist of ethylene oxide and propylene oxide monomer units in, in some cases, randomly mixed sequence and in which the ethylene oxide fraction must not be more than 60 mol %, in order to prevent the formation of polyethylene glycol blocks in the polymer chain.
• the fact that, furthermore, surfactant-active polyether siloxanes are prepared only by using blends of at least two DMC-based EO/PO polyetherols of different molar mass demonstrates that a very narrow molar mass distribution predetermined by the DMC technology according to the present prior art is in no way advantageous in the field of PU foam stabilizers.
• the technical problem to be solved is thus defined as that of finding a process for DMC-catalyzed preparation of polyethers, which permits, by a chemical route, by intervention into the catalysis mechanism and irrespective of the reactor type (stirred reactor, loop reactor, ejector, tubular reactor or, for example, reactor battery) and process principle (batchwise mode or continuous process), molar mass distributions to be accessed in a controlled and reproducible manner according to the requirements of the desired field of use, and even polyethers to be prepared with a defined elevated polydispersity M w /M n which is different if compared to polyethers produced by known processes.
• the process according to the invention preferably aims to prepare polyethers which are suitable directly themselves as interface-active compounds or else as precursors for preparing surfactants.
• the invention does not intend to encompass within the scope of the invention any previously disclosed product, process of making the product or method of using the product, which meets the written description and enablement requirements of the USPTO (35 U.S.C. 112, first paragraph) or the EPO (Article 83 of the EPC), such that applicant(s) reserve the right and hereby disclose a disclaimer of any previously described product, method of making the product or process of using the product.
• Si—H-additive is used in a concentration level of 0.01 to 3 percent per weight, preferred 0.01 to 1 percent per weight, based in the total mass of the (produced) polyetheralcohols.
• the catalyst concentration is preferably >0 to 1.000 ppmw (ppm by mass), preferably >0 to 500 ppmw, more preferably 0.1 to 100 ppmw and most preferably 1 to 50 ppmw. This concentration is based on the total mass of the (produced) polyether polyols; the reaction temperature is 60 to 250° C., preferably of 90 to 160° C. and more preferably at a temperature of 100 to 130° C.
• the pressure at which the alkoxylation takes place is preferably 0.02 bar to 100 bar, preferably 0.05 to 20 bar absolute.
• Si—H-additive results in a significant broadening of the distribution in molar masses and a significant higher polydispersity of the resulting end products.
• the polydispersity of the produced polyetheralcohols using the inventive process is preferred at least 10 percent higher, more preferred at least 20 percent higher and most preferred at least 30 percent higher compared to an alkoxylation process performed without the Si—H-additive using the same reaction conditions. This result is nearly independent from the reaction conditions like for example the temperature, catalyst concentration of polymerization/alkylation time.
• the polydispersity is preferred at least 0.1 higher, more preferred at least 0.2, and most preferred at least 0.4 higher using the Si—H-additive using the same reaction conditions.
• the absolute value of the change in polydispersity is e.g. as known to the artisan dependent from the concentration of the catalyst, the reaction time/duration, the concentration of the Si—H-additive, the starting alcohol and the resulting chain length of the polyetheralcohol produced.
• the polyether alcohols prepared using the same reaction conditions but without the Si—H-additive will show for comparison polydispersities of 1.05 to 1.15.
• higher molecular polyether alcohols having an average molecular mass of higher than 8.000, prepared by using the inventive process and the starting compounds above having polydispersities of higher that or equal to 1.4.
• the polyetherols The polyether alcohols prepared using the same reaction conditions but without the Si—H-additive will show for comparison polydispersities of nearly 1.1 and in very special cases up to 1.3.
• a process is thus provided for preparing polyether alcohols with elevated polydispersity by polymerization by means of double metal cyanide catalysts (DMC catalysts), in which, before or during the polymerization, one or more, optionally mixed Si—H additives (in the following also referred to as additive only) consisting of compounds having one or more (hydridic) hydrogen atoms on one silicon atom, are added.
• DMC catalysts double metal cyanide catalysts
• the covalent hydrogen-silicon bond exhibits a negative polarization of the hydrogen.
• This hydrogen is thus of hydridic nature and can react in an active manner, for example, with other H-acidic compounds (with release of hydrogen).
• Elevated polydispersity is understood to mean the difference in the M w /M n value which arises from the comparison between the value in the case of (normal) standard DMC catalysis to that in the case of additional use of an inventive additive. According to the starter compound used, even a small increase in the value may be significant and positively influence the desired properties of the polymerization product.
• silanes to be used with preference as additives in accordance with the invention are compounds of the general formula (I) R′′′ a H b Si (I),
• a nonexclusive list of such inventive silane additives of the formula (I), which can be used alone or in mixtures with one another or in combinations with hydrosiloxanes of the formula (II), comprises: monomethyl, dimethyl- and trimethylsilane, monoethyl-, diethyl-, triethylsilane, monopropyl-, dipropyl-, tripropylsilane, monophenyl-, diphenyl-, triphenyl-silane, phenylmethyl- and phenylethylsilane, phenyldimethyl- and phenyldiethylsilane, monomethoxy-, dimethoxy- and trimethoxysilane and monoethoxy-, diethoxy-, and triethoxysilane, dimethylmethoxysilane, methyldimethoxysilane and, for example, tris(trimethylsilyl)silane.
• hydrosiloxanes which are likewise used with preference as additives in accordance with the invention in addition to the silanes specified in formula (I) are polyorganosiloxanes of the general formula (II)
• R is one or more identical or different radicals selected from linear or branched, saturated, mono- or polyunsaturated alkyl, alkoxy, aryl, alkylaryl or arylalkyl radicals having 1 to 40 carbon atoms, in particular 1 to 20 carbon atoms, or haloalkyl groups having 1 to 20 carbon atoms, or siloxy groups and triorganosiloxy groups, where
• inventive additives with hydridic hydrogen are capable of influencing the mechanism of action of the double metal cyanide catalyst in a way that permits the kinetics of the chain growth to be modified and, according to the additive concentration and type, polydispersities of different magnitudes to be accessed.
• inventive additives with hydridic hydrogen are capable of influencing the mechanism of action of the double metal cyanide catalyst in a way that permits the kinetics of the chain growth to be modified and, according to the additive concentration and type, polydispersities of different magnitudes to be accessed.
• the particular additive is added to the reaction mixture in such a low concentration that it can remain in the finished polyether without any adverse effect on the product quality.
• the additive is added preferably in one portion at the beginning of the alkoxylation before the start of the metered addition of alkylene oxide, but can alternatively also be added continuously (for example dissolved/dispersed in the feed stream of the reactant(s)) and also in several portions during the continuous addition of alkylene oxide.
• the epoxide monomers usable in the context of the invention may, as well as ethylene oxide, propylene oxide, butylene oxide and styrene oxide, be all known further mono- and polyfunctional epoxide compounds, including the glycidyl ethers and esters, and individually or else as a mixture, and either randomly or in blockwise sequence.
• a reaction mixture which comprises the DMC catalyst, optionally slurried in a suspension medium, is initially charged in the reactor and at least one alkylene oxide is metered into this system.
• the molar ratio of alkylene oxide to reactive groups, especially OH groups, in the start mixture in this case is a range selected from the group consisting of 0.1 to 5:1 and 0.2 to 2:1. It may be advantageous when, before the addition of the alkylene oxide, any substances present which inhibit the reaction are removed from the reaction mixture, for example by distillation.
• the suspension media utilized may either be a polyether or inert solvents, or advantageously also the starter compound onto which the alkylene oxide is to be added, or a mixture of the two.
• the start of the reaction can be detected, for example, by monitoring the pressure.
• a sudden drop in the pressure in the reactor indicates, in the case of gaseous alkylene oxides, that the alkylene oxide is being incorporated, the reaction has thus started and the end of the start phase has been attained.
• the start phase i.e. after initialization of the reaction, according to the target molar mass
• either starter compound and alkylene oxide at the same time or only alkylene oxide are metered in.
• the reaction can be carried out in an inert solvent, for example for the purpose of lowering the viscosity.
• the molar ratio of the alkylene oxides metered in, based on the starter compound used, especially based on the number of the OH groups in the starter compound used is 1 to 106:1.
• the alkylene oxides used may be compounds which have the general formula (IIIa)
• R 2 or R 3 , and R 5 or R 6 are the same or else independently H or a saturated or optionally mono- or polyunsaturated, optionally mono- or polyvalent hydrocarbon radical which may also have further substitution, where the R 5 or R 6 radicals are each a monovalent hydrocarbon radical.
• the hydrocarbon radical may be bridged cycloaliphatically via the fragment Y;
• Y may be a methylene bridge having 0, 1 or 2 methylene units
• R 2 or R 3 are independently a linear or branched radical having 1 to 20, preferably 1 to 10 carbon atoms, which includes but is not limited to a methyl, ethyl, propyl or butyl, vinyl, allyl radical or phenyl radical.
• At least one of the two R 2 or R 3 radicals in formula (IIIa) is hydrogen.
• Y as the alkylene oxides, ethylene oxide, propylene oxide, 1,2- or 2,3-butylene oxide, isobutylene oxide, 1,2-dodecene oxide, styrene oxide, cyclohexene oxide (here, R 2 -R 3 is a —CH 2 CH 2 CH 2 CH 2 — group, and Y is thus —CH 2 CH 2 —) or vinylcyclohexene oxide or mixtures thereof.
• hydrocarbon radicals R 2 and R 3 according to formula (IIIa) may themselves have further substitution and bear functional groups such as halogens, hydroxyl groups or glycidyloxypropyl groups.
• alkylene oxides include epichlorohydrin and 2,3-epoxy-1-propanol.
• glycidyl compounds such as glycidyl ethers and/or glycidyl esters of the general formula (IIIb)
• glycidyloxypropyl group is bonded via an ether or ester function R 4 to a linear or branched alkyl radical having 1 to 24 carbon atoms, an aromatic or cycloaliphatic radical.
• This class of compounds includes, for example, allyl glycidyl ether, butyl glycidyl ether, 2-ethylhexyl glycidyl ether, cyclohexyl glycidyl ether, benzyl glycidyl ether, C12/C14-fatty alcohol glycidyl ether, phenyl glycidyl ether, p-tert-butylphenyl glycidyl ether or o-cresyl glycidyl ether.
• Glycidyl esters used with preference are, for example, glycidyl methacrylate, glycidyl acrylate or glycidyl neodecanoate. It is likewise possible to use polyfunctional epoxide compounds, for example 1,2-ethyl diglycidyl ether, 1,4-butyl diglycidyl ether or 1,6-hexyl diglycidyl ether.
• the starters used for the alkoxylation reaction may be all compounds R 1 —H (IV) (the H belongs to the OH group of the alcohol) which, according to formula (IV), have at least one reactive hydroxyl group.
• starter compounds are understood to mean substances which form the beginning (start) of the polyether molecule to be prepared, which is obtained by the addition of alkylene oxide.
• the starter compound used in the process according to the invention is preferably selected from the group of the alcohols, polyetherols or phenols or acids.
• the starter compound used is preferably a mono- or polyhydric polyether alcohol or alcohol R 1 —H (the H belongs to the OH group of the alcohol).
• the OH-functional starter compounds used are preferably compounds having molar masses of 18 to 2000 g/mol, especially 100 to 2000 g/mol, and 1 to 8, preferably 1 to 4, hydroxyl groups.
• Examples include but are not limited to allyl alcohol, butanol, octanol, dodecanol, stearyl alcohol, 2-ethylhexanol, cyclohexanol, benzyl alcohol, ethylene glycol, propylene glycol, di-, tri- and polyethylene glycol, 1,2-propylene glycol, di- and polypropylene glycol, 1,4-butanediol, 1,6-hexanediol, trimethylolpropane, glycerol, pentaerythritol, sorbitol, or compounds which bear hydroxyl groups and are based on natural substances.
• low molecular weight polyetherols having 1-8 hydroxyl groups and molar masses of 100 to 2000 g/mol which have themselves been prepared beforehand by DMC-catalyzed alkoxylation, are used as starter compounds.
• suitable compounds are any having 1-20 phenolic OH functions. These include, for example, phenol, alkyl- and arylphenols, bisphenol A and novolacs.
• the process according to the invention can be used, according to the epoxide and the type of epoxide ring opening, to prepare polyether alcohols of the formula (Va) and (Vb) and mixtures thereof.
• R 1 [(CR 6 R 2 —CR 5 R 3 —O) n H] m (Va) or R 1 —[(CR 5 R 3 —CR 6 R 2 —O) n H] m
• R 1 is either a hydroxyl radical or a radical of the organic starter compound and, in this case, is a radical having at least one carbon atom
• the process according to the invention can be used to synthesize polyethers of the formula (Va) or (Vb) which are notable in that they can be prepared in a controlled and reproducible manner with regard to structure and molar mass distribution.
• These polyethers are suitable as base materials for preparing, for example, polyurethanes, and are particularly suitable for preparing products with interface-active properties, including, for example, but not specified exclusively, organically modified siloxane compounds.
• These surfactants include—but without being limited thereto—silicone polyether copolymers as PU foam stabilizers, and equally emulsifiers, dispersants, defoamers, thickeners and, for example, release agents.
• alkylene oxides and glycidyl compounds used, the composition of mixtures of these epoxide compounds and the sequence of their addition during the DMC-catalyzed alkoxylation process depends on the desired end use of the polyether alcohols.
• the reactors used for the reaction claimed in accordance with the invention may in principle be all suitable reactor types which allow the reaction and any exothermicity thereof present to be controlled.
• the reaction can, in a manner known in process technology, be effected continuously, semicontinuously or else batchwise, and can be adjusted flexibly to the production technology equipment present.
• the product can be worked up.
• the workup required here includes in principle only the removal of undepleted alkylene oxide and any further, volatile constituents, typically by vacuum distillation, steam or gas stripping or other methods of deodorization. Volatile secondary components can be removed either batchwise or continuously.
• DMC catalysis in contrast to the conventional base-catalyzed alkoxylation, it is normally possible to dispense with a filtration.
• the alkylene oxide compounds or, stated in general terms, epoxide compounds are added at a temperature range selected from the group consisting of 60 to 250° C., 90 to 160° C. and 100 to 130° C.
• the pressure at which the alkoxylation takes place is selected from a range consisting of 0.02 bar to 100 bar and 0.05 to 20 bar absolute. By virtue of the performance of the alkoxylation under reduced pressure, the reaction can be performed very reliably. If appropriate, the alkoxylation can be carried out in the presence of an inert gas (e.g. nitrogen) and also at elevated pressure.
• an inert gas e.g. nitrogen
• the process steps can be conducted at identical or different temperatures.
• the mixture of starter substance, DMC catalyst and optionally additive initially charged in the reactor at the start of the reaction can, before commencement of the metered addition of the alkylene oxides, be pretreated by stripping according to the teaching of WO 98/52689 (U.S. Pat. No. 5,844,070).
• an inert gas is added to the reaction mixture via the reactor feed, and relatively volatile components are removed from the reaction mixture by applying a reduced pressure with the aid of a vacuum system attached to the reactor system.
• the addition of inert gas and the simultaneous removal of the relatively volatile components may be advantageous especially at the startup, since the addition of the reactants or side reactions can also allow inhibiting compounds to get into the reaction mixture.
• the DMC catalysts used may be all known DMC catalysts, preferably those which comprise zinc and cobalt, more preferably those which comprise zinc hexacyanocobaltate (III). Preference is given to using the DMC catalysts described in U.S. Pat. No. 5,158,922, US 20030119663, WO 01/80994 (U.S. Pat. No. 6,835,687) or in the abovementioned documents.
• the catalysts may be amorphous or crystalline.
• the catalyst concentration is selected from the ranges consisting of >0 to 1000 ppmw (ppm by mass), >0 to 500 ppmw, 0.1 to 100 ppmw and 1 to 50 ppmw. This concentration is based on the total mass of the polyether polyols.
• the amount of catalyst should be adjusted such that there is a sufficient catalytic activity for the process.
• the catalyst can be metered in as a solid or in the form of a catalyst suspension. Where a suspension is used, especially the starter polyether is suitable as the suspension medium. However, preference is given to dispensing with a suspension.
• the polydispersity M w /M n is increased from about 10% to about 40% when a silicon compound with one or more hydrogen atoms bonded directly to the silicon atom is used as an additive to the starter mixture composed of OH-functional starter and DMC catalyst relative to a starter mixture without the additive. In another embodiment of the invention, the polydispersity M w /M n is increased from about 20% to about 30% when a silicon compound with one or more hydrogen atoms bonded directly to the silicon atom is used as an additive to the starter mixture composed of OH-functional starter and DMC catalyst relative to a starter mixture without the additive. Depending on the reaction conditions and the additives used, even higher increases of polydispersity may be reached/expected, e.g. from about 40% to about 100%-200%.
• the values in percentage and absolute numbers of the GPC measurements are based on typical GPC-conditions: column combination SDV 1000/10000 ⁇ (length 65 cm), temperature 30° C., THF as mobile phase, flow rate 1 ml/min, sample concentration 10 g/l, RI-detector, analysis against polypropylene glycol standard.
• the reactor is evacuated down to an internal pressure of 30 mbar in order to remove any volatile ingredients present by distillation.
• To activate the DMC catalyst a portion of 40.0 g of propylene oxide is added.
• the resulting long-chain polypropylene glycol has an OH number of 10.2 mg KOH/g, a viscosity (25° C.) of 10 400 mPas and, according to GPC (gel permeation chromatography), a polydispersity M w /M n of 1.8 (against polypropylene glycol standard).
• the resulting long-chain, low-viscosity polypropylene glycol has an OH number of 9.8 mg KOH/g, a viscosity (25° C.) of 7100 mPas and, according to GPC, a polydispersity M w /M n of 1.4 (against polypropylene glycol standard).
• the polydispersity using the additive in the process is compared to the reference experiment higher by 0.4, which is corresponding to 28.6 percent.
• the reactor is evacuated down to an internal pressure of 30 mbar, in order to remove any volatile ingredients present by distillation.
• To activate the DMC catalyst a portion of 36.0 g of propylene oxide is added.
• the resulting allyl polyether has an OH number of 13.5 mg KOH/g and, according to GPC, a polydispersity M w /M n of 1.5 (against polypropylene glycol standard).
• the resulting allyl polyether has an OH number of 13.4 mg KOH/g and, according to GPC, a polydispersity M w /M n of 1.3 (against polypropylene glycol standard).
• the resulting allyl polyether has an OH number of 13.5 mg KOH/g and, according to GPC, a polydispersity M w /M n of 1.5 (against polypropylene glycol standard).
• the resulting allyl polyether has an OH number of 13.4 mg KOH/g and, according to GPC, a polydispersity M w /M n of 1.5 (against polypropylene glycol standard).
• the resulting allyl polyether has an OH number of 13.4 mg KOH/g and, according to GPC, a low polydispersity M w /M n of 1.05 (against polypropylene glycol standard).
• the experimental overview 2 shows that the polydispersity by using the additive in experiments 2a), 2c) and 2d) is higher by 0.45 points or 42.8 percent if compared to the reference experiment 2e). In experiment 2b) the polydisperity is higher by 0.25 points or 23.8 percent if compared to the reference experiment 2e).

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